The general requirements for constructing and operating a telecommunications network can vary considerably throughout the world, from one continent to another, from one country to another, and from one region to another. As an example, synchronous data communications in an optical network can use one of variety of physical layer communication protocols (e.g., Synchronous Optical Network (SONET) or Synchronous Digital Hierarchy (SDH)). SONET is the standard for optical transport of synchronous data communications in North America and SDH is the European variant. The SONET standard is similar to the SDH standard in many respects. For example, SONET and SDH each uses time-division multiplexing (TDM) to aggregate multiple low-order data blocks into high-order data blocks, called frames (e.g., Synchronous Transport Signal (STS) frames). However, one significant difference between the standards is the basic unit of payload data. In SONET, the basic unit is an STS-1, which corresponds to a signal rate of approximately 50 Mbit/s. In SDH, the basic unit is an AU-4 with a signal rate of approximately 150 Mbits/s. Further, low-order SONET data blocks, called Virtual Tributaries (VTs), can have different signal rates than low-order SDH data blocks, called Tributary Units (TUs).
In addition to these and other signal rate differences, different national and regional markets throughout the world can have different physical requirements regarding the size of the network elements and the racks into which the network elements are arranged. Another difference concerns the direction in which the cooling system can exhaust air. Further, as another example, North American standards permit input/output (I/O) connections to terminate at the rear-side of the rack, a practice not typically followed by European standards.
To be able to supply network elements that satisfy the requirements of the various global markets, the telecommunications industry typically offers distinct product lines. These often include, for example, one product line for SDH-compliant product and another for SONET-compliant product. The management of separate staffing, accounting, and component inventories for multiple product lines can consequently lead to higher costs. Accordingly, it is advantageous to provide a network element that is configurable for deployment in a global variety of communications networks.